To do this we put the parts on our CMM and scanned them with the LC15Dx (probe accuracy of +/- 2.5 microns). We scanned them using this as accuracy is very important particularly when reverse engineering gears, as due to the nature of gears, a dimension being only a little bit wrong would be exaggerated from the function of a gear, as dimensions tend to be repeated all the way around.
Most of the gears had no problem with the scanning, however there was one with very deep curved teeth where the curve would block the line of sight for the scanner. This proved a difficulty when it came to modelling this gear.
A lot of time was spent in modelling each of these to make sure that the rounded dimensions that we modelled the part too were the design intent. For the gear with the curved teeth, our customer was happy with us cutting off one of the teeth so there was a clear line of sight. When we scanned this part and added the information we had no problem in the end with modelling the complete gear.
The customer was very pleased to receive CAD files of all the parts.